1. Field of the Invention
This invention relates to thermoformed articles and methods of manufacture thereof and, more particularly, to fastener devices for securing such thermoformed articles to support structures. Specifically, the present invention relates to an improved fastening device which is integrally formed with the thermoformed components at the time of formation of the thermoformed article.
2. Description of the Prior Art
Many situations arise where it is desirable to cover irregular surfaces with carpeting material. A common example of this is to cover the trunk of a car with a carpeting material as well as trim areas such as door panels, dash components and the like. In order to work well, such a carpeting material must be capable of taking on irregular, uneven shapes. It must have good hand feel, it must look good, and it must be resistant to the effects of water and soil.
In response to this need, carpet-like material and components have been constructed out of nonwoven, synthetic fibers. These fibers are easy to shape in contour around irregular and uneven surfaces, and if the carpet-like material is attached to a suitable substrate with the appropriate thermal response characteristics, a piece of material can be molded under conditions of pressure and heat to take on the general outline of the area to be carpeted. This particular process is known as thermoforming and has become quite popular in the nonwoven carpet industry. In addition, ways of manufacturing such carpeting as well as cutting and molding the carpeting to a given shape have been developed. One common approach is to make a soft bulky assembly of fibers, known as a batt, and then attach the batt to carpeting that has been produced from a nonwoven or other available technology. The carpet is attached by a needle loom by pushing the needle downwards into the bulk of fibers. The needle has downwardly-facing barbs on it. In a reverse-fishook principle, the barbs that are being pushed in a downward direction tend to catch fibers and pull them downward so as to thoroughly entangle and intermix the fibers among each other. This results in a batt that has been compressed, and is less likely to fray. The process of running such fibers through the needle loom is commonly known as needle-punching, or simply needling. This particular process is discussed in more detail in U.S. Pat. No. 4,424,250, the disclosure and contents of which are specifically incorporated herein by reference, this particular patent being assigned to the assignee of the present invention.
Taking this process a step further, ways have been developed for making nonwoven fiber carpeting that has desirable carpet-like qualities, good hand-feel, an absence of fused, glossy or shiny surface areas which can be shaped around particularly sharp contours, and which have enough stiffness to cover vertical surfaces without having to be affixed onto such a surface. This particular concept evolved into a nonwoven, needle-punched carpeting which formed into a relatively rigid textile panel from a loosely consolidated, nonwoven fibrous batt. The batt may be composed of different types of fibers that have been chosen so that the needle-punching process tends to force one type of the fiber to the surface of the final product. In this manner, a particular substrate may be formed having a concentration of one type of fiber on one surface versus the opposite surface. This particular development is disclosed in U.S. Pat. No. 4,818,586, the contents of which are specifically incorporated herein by reference and which has been assigned to the assignee of the present invention.
Alternatively, a carpet may be attached to a nonwoven substrate which may differ in chemical composition from the carpet face via the needle-punching process. Upon exposure to conditions of suitable heat and pressure, the composite will form a relatively rigid panel or shape.
Once a substrate component of sufficient rigidity and contour has been formed, there remains the problem of attaching the component to a support frame or assembly, such as a trunkliner or door panel structure. Attaching mechanical fasteners to automotive trim parts is therefore a necessary fact in the production of these materials. In the past, one form of attaching such fasteners has been simply to glue or in some other way physically attached a fastener to the back surface of the substrate component in a separate procedure, such as by using hot melt adhesives and the like.
In another system, certain substrates are formed by undergoing extremely high pressure and temperature during the molding cycle and are able to use fasteners that are embedded in the substrate during the material flow achieved in the forming stage. An advantage to this technique is that the placement of the fastener is consistent from part to part as well as avoiding a separate, off-line assembly operation. However, in the past this procedure has only been available for high pressure, high temperature processes which cause material flow during substrate formation so as to embed the fastener within the actual substrate itself. This process has not been usable with low pressure, thermoformed parts where molding of the substrate is accomplished only with latent heat of the substrate, since the molds themselves are nonheated. The above process cannot be used in such low pressure thermoformed operations due to the lack of substantial material flow during the forming operation. Thus, there remains a need to provide a fastening system wherein fasteners may be integrally formed with the thermoformed components during on-line assembly formation of the component article.